US2608534A - Heteropoly acids or salts thereof as catalysts - Google Patents

Description

Patented Aug. 26, 1952 HETEROPOLY ACIDS R SALTS THEREOF AS CATALYSTS Raymond N. Fleck, Long Beach, Calif., assignor to Union Oil Company of California, Los Angelcs, Calif., a corporation of California No Drawing. Application April 18, 1949, Serial No. 88,224

is Claims. (01. 252-435) This invention relates to catalysts and catalytic processes for processing various hydrocarbons and hydrocarbon mixtures. More particularly the invention relates to new and improved catalysts to be employed in these hydrocarbon conversion processes and further to the methods of preparing these catalysts.

The treatment of various hydrocarbons with catalysts to produce changes therein is well known in the art. The particular catalysts employed, temperatures and pressures of operation and other related factors serve to determine particular reactions taking place in the hydrocarbon feed. Many of these processes utilize a solid catalyst of granular, pelleted, powdered or other form, and for this reason these processes are termed heterogeneous catalytic conversion processes. Included in this group for example, are catalytic cracking, dehydrogenation, hydrogenation, desulfurization, hydroforming, aromatization, certain alkylation and isomerization processes, addition reactions and the like. For these processes many catalysts have been employed with varying success. In most cases, although such is not always the case, these catalysts comprise a catalytic agent distended on a suitable carrier or support. Such catalytic agents have included the oxides or other compounds of the metals such as chromium, molybdenum, cobalt, nickel, zinc, lead, cadmium, vanadium, manganese, tantalum, tungsten, titanium, platinum, columbium, scandium, thorium, uranium, zirconium, tin, copper, etc, which compounds may be produced by an appropriate treatment of the chromates, molybdates, vanadates, sulfates, nitrates, chlorides and other suitable salts of the metals by methods well known in the art. Many of these catalytic agents are effective only when supported on such carriers as alumina, magnesia, magnesium hydroxide, silica, zirconia, titania, zinc oxide, thoria, or a combination of one or more of these. Certain of these processes, however, may employ a catalyst comprising predominantly a catalytic agent in the absence of a carrier or supporting material. Thus, for example, a desulfurization process may be affected in the presence of a catalyst comprising the combined oxides of cobalt and molybdenum, i e.

cobalt molybdate, in powdered, pelleted or gran=- ular form in the absence of the alumina-silica carrier. However, catalysts supported on such a carrier are generally found to be equally and in many instances more effective than those catalysts consisting entirely of the catalytic agent and at the same time are considerably less expensive.

Many methods of preparation of these heterogeneous catalysts have been utilized including impregnation, ooprecipitation, mechanical mixing, sublimation and the like. In preparing such a catalyst by impregnation the carrier in the form of powder, granules or pellets is immersed in a solution of a suitable soluble salt of a desired metal such as ammonium molybdate, chromium nitrate, ammonium dichromate, ammonium vanadate,- ammonium tungstate, cobalt nitrate, and the like, whereupon the carrier having adsorbed a portion of the solution. is dried and calcined at a teperature in the range of about 400 C. to about 700 C. to convert the adsorbed salt to the oxide of the metal or metals employed. In preparing a catalyst by coprecipitation the process embodies a simultaneous pre cipitationof the hydrated oxide of the carrier and the hydrated oxide or oxides of the desired catalytic agents from a solution containing appropriate amounts of suitable soluble salts of the carrier type material and the metal or metals employed as catalytic agent. A modification of this procedure consists of precipitating the hydrous oxides of the catalytic agents in the presonce of a wet carrier gel.

There are certain factors which need be critically examined when selecting the catalyst to be employed in any of the hydrocarbon conversion processes including, the expense of the catalyst; the relative activity of the particular catalyst in comparison to others which may be employed; the mechanical strength of the catalyst particles or granules and the effective life of the catalyst at the conditions of temperature and pressure employed in the operation. Each of these factors are interrelated and a deficiency in one may be compensated for by relative proficiency in one Or more of the others. However,

one of the most important of these is the life of the catalyst in operation.

The catalyst life appears to be a function of its composition and the temperatures to which it is subjected and it is toward the former of these that the present invention is primarily directed. A laboratory evaluation procedure for measuring the relative life expectancy of a catalyst has been developed and is widely used in the art. This procedure consists in subjecting samples of the catalyst in question to high temperature heat treatments for given periods of time and subsequently ascertaining the activity of the heat treated catalyst in relation to the activity of the catalyst prior to this heat treatment. Exact predication of the catalyst life on the basis ofthese heat treatments is as yet im- 3 possible, but it has been found that the relative life expectancy of the various catalysts may be determined by a comparison of their heat stability characteristics.

During extended usage of catalysts of the type described a gradual loss in catalyst activity occurs which is generally accompanied by other changes of a physical nature such as loss of mechanical strength, decrease in eflective sunface area, changes in the pore size distribution and the like. The explanation for the loss in catalytic activity and attendant changes is un certain and in any case comparatively-complex but it is apparently tied up with various operatlonal factors such as the temperature, :both of.

the reaction and the regeneration, cooling :rates and the like. It has been found that these various changes in the catalyst can be induced by high temperature heat treatments for comparativelyshort periods of time. .Thusonestandard measure of a catalysts expected life characteristics is obtained by heating a sample .of the 7 catalyst for a period of six hours at a temperature of 800 C. The heat treated sample and a sample-of the fresh catalyst are then tested for activity in the particular reaction for which the catalyst was prepared and the loss inactivity exhibited by the heat treated catalyst is compared with results of similar tests on other catalyst samples to give a picture of the relative stability of the catalyst under examination.

The exact causes for the degradation of a catalyst during continued operation or in the heat stability test as above described has not been definitely determined but it is commonly accepted thata change in the structure of the catalyst or carrier plays at least a large part .in this loss of activity. For example X-ray diffraction datahave shown that the loss of activity of an alumina-supported catalyst is accompanied by a crystalgrowth within the catalyst and a resultant destruction of the gamma or more active form of alumina. However, in the absence of a-cataly'tic agent, such an alumina carrier is stable with respect to the destruction of the gamma 'alumina'at temperatures ashigh as 1,000 E. 'But'this efiect is considerably altered when aicata'lyticagent isdistended on thesame aluminaand it is with this aspect of the catalyst problem that the present invention is primarily concerned. Apparently the effect of a catalytic agent on the alumina or 'on other carriers is to accelerateor possibly'even catalyzelthe crystal growth, theloss in surface area and other related factorswhich'may contribute to the loss in catalyst activity.

This effect has been shown many times over and C particularly observable in catalyst surface area studies in which I have-foundthat alumina containing approximately 12% of ,distended molybdenum .oxide loses substantially all of its surface area when measured by the method of Brunauer, Emmett .& Teller (J. Am. Chem. Soc. 60, 309 (1938) employing nitrogen as the adsorbate after a six hourheat treatmentat 900" C. In the absencepjf the distended molybdenum oxide-however, 'the samealumina .will show a *thus destroying the activity of the carrier. present invention is based primarily on the prin- 4 the carrier, inasmuch as the lower the percentage of the catalytic agent, the greater will be the heat stability of the catalyst. This, however, is of limited value in the present art inasmuch as it has been found that certain percentages of the catalytic agent are necessary in order to attain an economically feasible catalytic activity even at the expense of a catalyst of shorter life. It may be postulated that the active catalytic agent present on the alumina undergoes a reversible chemical reaction with the alumina, The

c'iple of distending on the support or carrier material a form of-the catalytic agent which will "be incapable or at least less capable of catalyzing catalytic agents'have been .distended which subsurface .area, measured as above, .of ,approxim'atelyf162 square meters per. gram after calcinastitution-is made possible :byrthe improved heat stability of the catalysts containing the.ca'-talytic agents .of :my invention.

Another object of the invention is .to-provide a class of catalysts in which the catalytic agent comprises a heteropoly acid or a metalsalt of a heteropoly acid.

A still further-object of the present invention is to provide a method of preparing catalysts for these'h-ydrocarbon conversion processes having improved heat stability characteristics which involves new and simplified methods of synthesizing and utilizing the heteropoly acids which heretofore have requiredlong and tedious preparation methods. It is emphasized, however, that the hereinafter disclosed catalysts-maybe prepared from heteropoly acids'by the methods of this'invention or other methods regardlessof the origin and synthesis methods of heteropoly acids themselves.

Hydrocarbon conversion processes -'may be divided into various narrower classifications. The term conversion is a broadone and'connotates any change in the structure of the molecules present in the feed stocks. These changes-vary depending upon the operating conditions and catalystsemployed in the treatment of the stock. Thus in one class of operation the predominate reaction is hydrogen exchange, 1. e. addition of hydrogen to the hydrocarbon molecules, withdrawing hydrogen therefrom or in some instances adding hydrogen to a portion ofthe feed at least partially at the expense of another portion of the feed. The processes which may be classed as hydrogen exchange processes include dehydrogenation, hydrogenation, hydroforming, 'aromatization and desulfurization. This latter process maybe classed in this group by virtue of the fact that the removal of the sulfur from the hydrocarbon molecule is accompanied by the introduction of hydrogen to take its] place. (A second class of 1 processes although class'ifiable'inj the above grouping is directed pri- "marily to a 'changein relative size of the molecules; Such processes may either reduce or increase thefmolecular sizexof the components of 'the feed and include the processesof cracking, falkylation, polymerization, condensation, and the like-and on the'basis of their primary function may be termedfmolecular reforming processes. A third class or isomerization process is unique in itself althoughof courseisomeri'zation takes place to a certain extent in the majority of the other Xhy'drocarbon'. conversion reactions, As :such, however, it is not the primary reaction in .these .otherprocesses. 'A fourth class of conversion process comprises the addition :.reactions such as nitration, chlorination,.bromination,hydration and the like. l '1 .1 :"Whereas, the-present invention contemplates the use 'of the catalysts as hereinafter described .in any of thehydrocarlcon conversion reactions, I have found that they have particular utility in tho'se,processesinvolving primarily hydrogen exchange including hydroforming, hydrogenation, dehydrogenation, desulfurization and aromatization inasmuch as in general these processes utilize catalysts'comprising a catalytic agent distended ion, a suitable carrier. Further, either during the reaction period or the regeneration period the catalysts employed in these processes are usuallysubjected to comparatively high tem- .peratures and as a consequence heatstability of the catalystsbecomes afactor of (majorimportance. V

. The, present invention comprises the use of the heteropoly acids orthe salts of the heteropoly acids as catalytic agents to beemployed as such or distended. on a suitable carrier material to be used in the above described catalytic processes. Thestructure of the heteropoly acids is difiicult of determination owing to the verylarge size of the molecule. The heteropoly acids may be best described as complex inorganic substances of high molecular, Weight in which two or more different acid "cations or oxides of metals or metal- ..loids areas sociated with varying, frequently indeterminate'jamounts of combined Water as water of,hydration. The molecular weightof these bodies may be as great as 3,000 or higher and they are comprised essentially of nuclear cations of such metals as copper, thorium, tin, cerium, cobalt, zirconium, titanium, and the like or such non-metals as boron, silicon, phosphorus and arsenic, surrounded by oxygen radicals of molybdenum, tungsten or vanadium. According to the work of Miolati (J; prakt. Chem. (2), 1908, 7'7, "417) substantiated by Illingworth and Keggin (J. Chem. Soc. 1935, 580) the typical acid atom of the heteropoly acid, that is, the phosphorus atom in phosphoheteropoly acids, the silicon atom in silico-heterop'oly acids, etc., is to be regarded as a central atom of a nucleus. This central atom i's hyd'rated and attached to six oxygen atoms, thus HqPOa, HsSIOe, etc. The oxygenis linked to 'the nuclear atom of phosphorus, silica, boron, arsenic or" the like in the same way that moleculesof ammonia are bound to the metalatom in the metallic aminos. The oxygen atoms can be wholly or partially substitutedby radicals such as-MoO, M0207, WOaWzOi, V2O5,"V2Oc. Thus we may form phosphomolybdicfacid, phosphoturrgstic acid, phosphovanadic acid and the like. The reasons for the existence of so many of these heteropplyacids are the possibilities of different ce'ntral atoms, and 'the presence of the different "acid radicals in the same molecule in varying degrees of saturation. Thus Imay employ phosphomolybdotung'stic acid in which molybdenum and tungsten containing radicals surround the central phosphorus atom, silicomolybdovanadic acid, titanomolybdotungstic acid and the like. In general the acids comprise the central atom surrounded by six or twelve molybdenum, tungsten, or vanadium radicals depending upon the oxidation state of the metal in the radical.

Further, I may employ the metal salts of these hete'ropoly acids as catalytic agents "such asfor example, cobalt phosphomolybdate, cadmium borotungstate, cadmium silicomolybdate; ferric silicomolybdate, ammonium vanadomolybdate, zinc phosphomolybdate, and thelike. Y

I have found that by employing the-appropriate heteropoly acid inthe preparation of the catalyst of the typ described hereinbeforethat the active catalytic agent is so boundby the central atom of the 'hetercpoly acid that the propensity to catalyze the destruction of the carrier during usage or heat stability testsis greatly minimized and the stability of the car"- rier approached that of the carrier in the absence of a catalytic agent. At the same time the presence of the central atom apparently has substantially no deleterious effect on the activity of the catalyst towards promoting the particular reaction desired, and in manycases ac tually enhances the activity thereof. The choice of the heteropoly acid to be employed is a function of the reaction to be catalyzed. Thus, as is well known, molybdenum oxide is an effective catalytic agent when distended on an alumina carrier for the promotion of the hydrocarbon conversion or hydrogen exchange reaction known as hydrcforming. In like manner. I have found, that a heteropoly acid or acid salt in which molybdenum containing radicals predominate when distended upon an alumina carrier is an excellent catalyst for this same reaction. and at the same time has a longer-effective catalyst life and correlatively a greater heat stability than does the, conventional molybdenum oxide on alumina hydroiorming catalyst. agents may include for example phosphomolybdic acid, silicomolybdic acid, germanomolybdic acid, chromiomolybdic acid, zinc phosphomolybdate, aluminum phosphomolybdate, aluminum silicomolybdate, titanium phosphomolybdate and the like. Similarly the combined oxides of cobait and molybdenum distended on a suitable support such as alumina has found application as a catalyst for the desulfurization of sulfur containing hydrocarbons and for this purpose I have found that the cobalt salt of a heteropolymolybdic acid such as cobalt phosphomolybdate, cobalt silicomolybdate, cobalt chromomolybdate, cobalt phosphomolybdovanadate, and the like, when distended on a similar carrier give a catalyst equally, if not more active and possessed of a longer eifective life and greater heat stability. "Other heteropoly acid catalysts may be employed for other reactions such as dehydrogenation, aromatization, cracking, hydration, polymerization, hydrogenation and the like, and in general I have found it preferable to employ aheteropoly acid or a heteropoly acid saltin which the predominant metal radical is the same as the preferable metal oxide or other compound employed as the catalytic agent in the conven tionalcatalyst forthe same type of reaction.

In general I have foundthat it is preferable to employ a heteropoly acidas the catalytic agent Such catalytic whichzcontainsLthersame metal ionfound to be --most eifective inrconventional catalysts .for the ,particularqreaction to-be catalyzed. In-addition, -:,howev,er,' other'ions'contained in the heteropoly :acidswor'its salt appear to be beneficial in the .final catalyst and by the use-of these acids many .groups'ofimetal ions which are incompatible in ordinary impregnation solution may be, distended :on the carrier intone operation. For example suchions as beryllium aluminum, thorium and 'iron cannot :ordinarily exist in solution with suchqionslas 'molybdate, tungstate and vanadate .due :to the precipitation therefrom of the hy- .,droxides, molybdates, tungstates or vanadates .of ,thesemetals. However, the-above metallic ions may be added -Lt;heteropoly acid solutions with- .out formation of a precipitate because of the complex-form of the molybdenum, tungsten, and vanadium ions. In this :manner a. soluble salt of f'the' above metals as for example the nitrates, chlorides, sulphates or thelike may be added to-aqueous solutions of these heteropoly acids :yielding with at least a portion of the added .metal ion a metal salt of the particular heteropoly.

acidor acids in'the solution. Further, if desired .thesoluble-salts of these metals may be added in-excess ofithe amount equivalent for salt formation with-the heteropoly acid Without formation of a precipitate. Thus for hydroforming, I have .found that catalysts comprising phosphomolybdic .orsilicomolybdic acids distended on alumina are .the most effective. For such catalysts I may em- ;ploy from about 2% to about 20% of the catalyticragent and about 80% to about 98% of the carrier, but preferably the amount of catalytic agent on thecarriershould be in the range of about 5% to about Although phosphoand= silicomolybdic acidsare the'preferred acids forzuse in hydroforming .catalysts I have also found that the :titanomolybdic acid, germane- .moly-bdic acid, and others are also eflective. Further, certain of the salts of the molybdic acids such" as aluminum phosphomolybdate, beryllium phosphomolybdate, titanium phosphomolybdate, zirconium .phosphomolybdate, chromium phosphomolybdate aswellas the corresponding salts of the silico-, titano-, germanoand stannomolybdatesarealso effective when employed as the catalytic agents in hydroforming catalysts. Of these saltsrit appears that the aluminum phosphoand silicomolybdates and the chromium phospho- .andesilicomolybdates are the most effective.

*Foraromatization or dehydrogenation catalysts ,I have found that best results are obtained if the chromium ion is present in the salt or in the acid either as the central ion of the heteropoly acid or as the addition ion in the metalsalt of the heteropoly acid. ThusI may employ catalysts comprising such catalytic agents as chromomolybdic acid or salts thereof, .chromovanadic acid, chromium 'phosphomolybdate, chromium .silicomolybdate, chromium phosphotungstate, chromium silicotungstate, chromium phosphomanadate, beryllium .chromomolybdate and the like, distended on a suitable carrier such as alumina, magnesia, thoria, titania, and the like, and of these the'preferableis alumina. In :these catalysts the catalytic agent may beemployed in amounts ranging'from about 3% to about 30% andpreferably in amounts ranging from about 25% -to about 15% with the complementary amount of the desiredcarrier.

In thedesulfurization of hydrocarbons employing asolid :type catalystbest results have been obtained-employing the heteropoly acids or other zinc .phosphovanadate, and the like.

:saltsfofwhich a cobalt ion is contained suchaas for; example, cobalt phosphomolybdate, cobalt silicomolybdate, @cob'alt phosphomolybdovanadate in whichraportion of the molybdenum oxide-in a heteropoly molybdic acid isrreplaced by-vanadium, cobalt phosphotungstate, 1 cobalt *titanomolybdate, iandthel ike. Althou'ghthe cob'alt containing agents .arethe preferred ones for-the 'desulfurization-proces other of the heteropoly acids and salts-and.particularly'those containing tungsten are effective catalytic agents .:such :as

for example .nickel stannotung'state, xstanno- .tungstic acid, phosphotungstic acid, nickel silicotungstate, nickel. horotungstate, germanotungstic molybdovanadate, stannic ph'osphotungstovanadate,'andthe like.

The catalysts according to the present invention containing as they do :catalyticallyactive agents in combined form possess 'greater'heat stability and longer effective catalytic li-fe,'in-

creasedactivity in manycases, lower oarbomdepositionwhen operating at relatively high temperatures .and equally important the property-0'1 permitting the usage of impure carrier materials.

As pointed out above catalytic agents as normally employed have "the effect of accelerating the destruction'of the=catalytic properties of the carrier material employed when exposed to long periods of usage'or comparatively'hightemperatures. Further, it has been foundfthatthepresence of certain'impurities in the carrier'such as sodium oxide, calcium oxide, magnesium oxide andthe like evenin relatively small amounts such as 1% to 5% or less has the effect in the presence of the catalytic agent of still further accelerating thispdestruction or degradationo'f thescarriermaterial. I have found'thatiby the usage of the catalytic agents herein. described comprising the heteropolyacids or the metal salts of the heteropol acids that the effects of-these impurities is also .minimized possibly as aresult of the combination of .these. impurities with the catalytic agent. It is postulated that suchde- .leterious components in the carrier'maypreferentially react with the heteropoly acid or 'itssalt to form for example such compounds as sodium phosphomolybdate, calcium 'phosphomolybdate, magnesium silicomolybdate and the like,'depending of courseupon the heteropoly acid or-salt-employed, and in'so doing become-effectively isolated from the-carrier and thereby lose their property of accelerating, or promoting thedegradation of the carrier. Whereas, I have foundxthat this effect is realized, the mechanism thereof'asdescribed represents only one possible explanation and is in no way intended tolimit my invention in this respect.

by the reaction, in the'first case, of-sodium phosphate andsodium'molybdate by careful acidification-and in-th second by the reaction of sodium silicateand' sodium molybdate uponacidification with hydrochloric acid. In .eithercase the extraction of theaqueous solution of the resultant acidwith ether results in the formation of an ether. complexuwith the acid whichseparates as a ;distinctphase from the. remainder of the solution. Removal of: the other from this separated phase' leaves the corresponding heteropoly acid. These methods, however, are to a certain extent objectionable when the acids producedare to be used inthepreparationof catalysts inasmuch as they are contaminated with sodium ionwhich are undesirable in the finished catalysts when present inexcessive amounts. Normally purification of the acids prepared in this manner is accomplished by :repeated recrystallization from Water withattendant difliculties and reduction of product yield.

In another methodof preparation of phosphomolybdic acid for example, freshly precipitated molybdenum oxide has been treatedwith phosphoric acid to yield the heteropoly acid free in this case from the undesirable sodiumion. I

withcheap readily'available chemicals to form an activestable phosphomolybdic acid. The unreacted molybdenum oxide-may of course be recycled and in this manner high yields of the heteropoly acid are obtained.

For example one batch of phosphomolybdic' acid was prepared by heating almost to boilingforone-half hour a mixture of 28 parts of sublimed molybdenumpxide, 6 parts of 85% phosphoric acid, 2 parts of concentrated nitric acid and ZOO-parts of water. A clear solution resulted which was decanted from the unreacted molybdenum" oxide which upon extraction with ether yielded approximately parts of the ether acid complex which contained approximately 8 parts of the acid." It is apparent that this method of preparation is simpler and results in a purer and less expensiv 'product than the methods heretofore employed.

lhe recommended procedure for the purifica tion of these acids and particularly those in which sodium ion is contained as a contaminate involves the isolation of the acid and recrystallization from water. I have found that a simpler and more economical purification is obtained by merely washing the ether extract with dilute nitric acid two to three times. The washed complex may then be diluted with water and theetherremoved by distillation, airblowing, or the like, to leave an aqueous acid concentrate free of "contaminating .ions such as sodium or chloride ions, which may be diluted and used to impregnate the catalysts as hereinafter described without further purification. Although the ether tion of silicomolybdic acid since ammonium sill-H extraction-of the acid is not always necessary in.

order to prepare the desired catalysts, I have found that shouldthe extraction be desirable other oxygen, nitrogen or sulfur compounds which form ccmplexes with the heteropoly acids may be used for the extraction such as for examplediisopropyl ether, diethylsulfide, pyridine, otherlorganic" amines and the like. Whereas, the abovedis'cussion pertaining to the preparation of the heteropoly acids has centered primarily} around the phosphoe and *sil'icoe molybdic. acids, suchemphasis is notintendedat'o, be indicative. of any limitations of my invention but was. merely used for descriptivepurposes inasmuch as other heteropoly acids such assilico.-., tungstic acid, germanovanadic acid and in gene; eral any of the earlier described heteropoly acidsmay be prepared by the method or methods; described. Still further, I, do not wishtoqbe limitedto thepreparation of any of these het eropoly acids by the methods disclosed, inasmuch; as they may be prepared in any mannerfdesired, to be. employed in the catalysts according to my; invention However, as far as I am ,awarethel method of preparation of the phosphomolybdic acid, employing sublimed rather than freshly precipitated yellow molybdenum oxide is new in the art and as such constitutes a portion of the present invention. 1 i

As described above the synthesis of jsilicoa molybdic acid or other silico-heteropoly acidsuby conventional means involves the acidification; with hydrochloric acid of a partially acidified solution of sodium molybdate and sodium si1icate.;v Both sodium and chloride ions present in excesr sive amounts are deleterious to any catalysts andas a consequence salts having ammonium or nitrate ions are employed in their place wherev ever possible in catalyst preparations. However," ammonium salts cannot be used for the prepara v cate is non-existent and ammonium silico-a molybdate is insoluble. The preparation ofa. low sodium silicomolybdic acid catalyst involves, therefore, an incomplete and comparatively. costly ether extraction to separate ythesilicomolybdic acid from the contaminating 1011s., {Io circumvent this diniculty I may prepare the silicomolybdic acid from sodium molybdate-and sodium silicate as above, employing nitric acid"- in place of hydrochloric acid. The resultant.- solution is subsequently diluted and passed; through an ion exchange to remove the sodium"? ions. The ion exchanged solution, contains only nitric acid, silicomolybdic acid and possibly small I amounts of silica and molydenum trioxide gelsj. and is satisfactory as such or upon dilution or concentration to impregnate carriers directly'orfi to be employed in the preparation of the'metalsalts of silicomolybdic acid, solutions of which: may subsequently be employed to impregnate the desired carrier. Ion exchangers usable: are; hydrogen zeolite, etc. Y Y1 If it is desired to employ as the catalytic agent a salt of a heteropoly acid rather thanthe acidlitself, this salt may be readilypreparedby simple reaction of the acid with a soluble salt of the T metal ion desired. Thus for example cobalt phosphomolybdate may be readily prepared'by simple mixing of a soluble cobalt salt such as cobalt nitrate, cobaltous fluoride, cobalt iodide} cobalt bromide, or the like, with the aque'ous phosphomolybdic acid. Alternatively thesalts may be prepared by direct synthesis without the intermediate step ofacid preparation. Thus cobalt carbonate, phosphoric acid and sublimed molybdenum trioxide may be reacted and t reaction products extracted with alcohohether, or the like to obtain directly'the cobalt phosph I molybdate complex from which the salt is 'ea'sily j isolated. Further freshly precipitated cobat phosphate may be reacted with freshly precipltated molybdenum and extracted with alcohol to again obtain cobalt phosphomolybdate complex. Probably the preferred method of preparing 11' these salts: and. particularly the salts of the phosphomolybdicacid involves the reaction as previously described of sublimed molybdenum trioxide with anexcess of phosphoric acidv in the presence of a small amount of nitric acid. to yield the phosphomolybdic acid which is contaminated with unreactedphosphoric acid and tothis mixture the desired. metal, ionrsuch as aluminum, zinc, colbalt, nickel, chromium. iron orthelike is addedto yield corresponding metal phosphomolybdate plus a precipitate of the corresponding metal phosphate. Such a procedure has considerable merit in that by simple control ofthe amounts of the metal ions added the reaction can be employed to remove excess phosphoric acid 'for'thepurification of the heteropoly acid or alternatively for the preparation and simultaneous purification of the corresponding metal salt. Thus in the preparation of the phosphomolybdic acid as described an excess of phosphoric a'cid is employed to accelerate the reaction between themolybdenum trioxide and the phosphoric acid. In certain cases the presence of the excess phosphate ion is undesirable in the prepara't'ion of the finished catalyst and to eliminate this certain purification procedures have been described such as extraction of the acid with ether or other organic compounds capable. of forming complexes therewith, by formation of insoluble salts with the heteropoly acid or the,

like. Another method of purification is apparent therefore in the above reaction whereby a sufiicient' quantity of a soluble salt, such as the nitrate, of -'a metalsuch as aluminum, zinc, iron or the like is added to form an insolubleprecipitate of the metal phosphate from which the acid may be readily separated and employed in catalystpreparationssubstantially free from the contaminating phosphoric acid. Similarly if it is desired to form the metal salt of the heteropoly acid an excess of the soluble metal salt may be added whereby the phosphoric acid is removed by precipitation of the phosphate and the excess salt will react with the heteropoly acid to form a.

soluble metal salt therewith whichis substantially free of undesirable phosphate ions.

Numerous methods may be employed for the preparation of the finished catalysts from these acids or from the salts of the acids, the choice of whichv will depend upon the available facilities and. methods used in preparing the catalytic agent and other related factors. The catalysts, according to the present invention, consist predominantly of a carrier upon which is distended in one manner oranother one or more heteropoly acidsas described, or one or more metal salts of these heteropoly acids or a mixture of metal salts and heteropoly acids. As carriers for these catalysts I may employ such materials as alumina, zirconia, silica, titania, magnesia, zinc oxide, thoria,;.or the like, and as pointed out about in general I prefer to employ the heteropoly acid or 'a salt of a heteropoly acid as the catalytic agent which contains the metal ion which has been found to be most suitable in conventional catalysts. The amount of the catalytic agent distended on the carrier in each case will, of necessity, be a function of the agent to be employed, the type of carrier employed, and the reaction to be catalyzed. Generally, however, it has been observed that these heteropoly acids or salts are'for a given per cent composition of the catalyst more eifectivethan an equivalent amount ofa catalytic agent comprising a metal oxide and ass. result'I may employ these catalytic agents such as dehydrogenation catalysts containing; chromium, reforming catalysts containing. vana-x dium and the desulfurization catalysts containing...

cobalt and molybdenum. I prefer to employ as, carriers for allof these reactionsaan alumina of either highly refined natureor of less refined: nature such asbauxite. In thisrespect the usage, of the catalytic agents herein disclosedpermits the use of the considerably less expensive bauxite in place, of the highly refined aluminaswhich have been; thought to be essential for suchreace t1ons as hydroforming, dehydrogenatiom (16:5

sulfurization, and the like.

The methods of preparing each of thesecatarlysts may be; divided into four classes of" pro cedure involving impregnation, mechanical, mix.-

ing, the formation of the activecatalytic agentj in situ bythe decomposition of an organiccome-s plex thereof or the formation of the active; catalytic agent in situ bythe decompositionof an inorganic complex thereof.

In the preparation of aqcatalyst by imgpregnae tion two alternative courses-of'procedureimaygbefollowed. One involves the isolation, and pu-ri;-: fication ofthe desiredheteropolyacid or-salt-and. subsequent immersion of the carrier-inset; water. solution of the catalytic agentfollowed-by cala.

cination to give the finalcatalyst, In, the alternative-method the carrier may beimpregnated directly with the unpurified acidror salt; during;:

any stage of the preparation, of the catalytic agent. Thus if the ether complex is obtained the. carrier may be impregnated directly with this...

complex as such preferably diluted with addie tional quantities ofether. preparational procedures, according tot-hisqine vention are followed the carrier may be 'im--- pregnated directly with the reaction product thus eliminating thesteps of ether extraction andpurification. Thislatter methodof impregnation is particularly applicable in thosecases where the heteropoly acid or the salt of the heteropoly acid is formed in the absence of. contaminating ions as for example asillustratedfin the preparation of the phosphomolybdic acid directlyfrom the phosphoric acid and molybdenumtrioxide-in the presense of nitric acid. In this case the liquid product may be removed from the undisfsolved molybdenum trioxide and thecata'lyst.

carrier, in any desired form such as pellets, po wder, granules or the like may be immersed'dl-I rectly in the liquid product inasmuch as Ih'avei found that the presence 'of the nitric acid and unreacted phosphoric acid have no detrimental;

effect on the final, catalyst in most cases, 'For this reason, generally I prefer to-usc those heteropoly acids or salts inwhich phosphoru'sfisj the central ion of the compound .inasmuchas such acids or salts may besoreadilyprepared.

in the absence of contaminating ionsandas are.- sult catalyst preparation is greatly cheapened.

However, it is to be understood thatflI do: notfl wish to be limited by this method of preparation, 7 inasmuch as other acids may bepreparedfreeof contaminating ions. Thus silicomolybdic acid.

may be prepared by commingling purified silica.

However, the.-

13 gel or a silica sol, molybdenum trioxide and nitric acid and heating these materials to comparatively high temperatures such as above 100 C. to about 200 C. under sufficient pressure to maintain the reacting solution in the liquid state. Further, I have found that the presence of the fluoride ion either as hydrogen fluoride or as the fluoride of themetal to be reacted has the effect of, accelerating or catalyzing the formation of v manyof theheteropoly acids. The above carriers may be used in the form oftheir oxides or the corresponding hydroxides or hydrated oxides.

The iollowing examples will serve to illustrate the preparation. of catalysts according to my invention by impregnation of the carrier material with the purified heterpoly acid or salt or with an impure heterpoly acid or salt, the latter group being preferably employed only when the impurities are not detrimental or may be removed from the catalyst by simple heat treatment.

EXAMPLE I A; catalyst comprising approximately 9.8% by weight. of silicomolybdic acid distended on bauxite was prepared by impregnating bauxite with a water solution of the purified silicomolybdic acid as follows: 100 parts of sodium molybdate was dissolved in 400 parts of water and heated to 60 C. after which 40 parts of concentrated hydrochloric acid was added. While rapidly stirring this solution a solution of parts of 40 Baum sodium silicate in 100 parts of H20 was slowly added. While stirring was continued 120 parts of concentrated hydrochloric acid was added. The resultant mixture was filtered and allowed to stand for 16 hoursafter which it was decanted from the solids and extracted with ether yielding 53 parts of an ether complex of the silicomolybdic acid. To further purify the complex it was mixed with 50 parts of water and parts of nitric acid and enough ether to separate the third phase. Approximately '70 parts of water was added to the complex after centrifuging and separation from the above mixture and ether was removed therefrom by warming and at the same time bubbling an air stream through the mixture. 1

A sample of 8 to mesh bauxite was calcined for two hours at 600 C. 266 parts of this calcined bauxite was immersed in a solution of 173 parts of the silicomolybdic acid prepared above, diluted to 300 parts with water. The carrier was immersed in this solution for a period of 45 minutes and subsequently dried at a temperature of about 180 F. for 16 hours and was activated by heat treatment for two hours at 600 C. to

yield a catalyst of the above composition.

EXAMPLE II I Another catalyst was prepared comprising approximately 8.5 per cent of phosphomolybdic acid distended on bauxite as follows: Phosphomolybdic acid was prepared by heating to a temperature of about 90 C. for about one hour, a mixture comprising 28 parts of sublimed molybdenum trioxide, 6 parts of 85% phosphoric acid, 2 parts of concentrated nitric acid and 200 parts of water. The resultant mixture was cooled and extracted with ether to yieldthe ether complex of the phosphomolybdic acid. The ether complex was mixed'with an equal volume of water and the ether removed by bubbling air through the mixture under vacuum to yield the concentrated .water solution of I the phosphomolybdic acid. Approximately 306 parts of'this concen- 14 I trated phosphomolybdic acid solution was diluted to 500 parts with distilled water and 480 parts of 8 to 20 mesh bauxite as used in the above Example L'which had been calcined for two hours at 600 C., was immersed in this solution. After a 45 minute immersion the im-. pregnated bauxite was removed from the solu-.

tion, dried for 16 hours at 200 F. and activated for two hours at 600 C. to give a catalyst of the above composition.

EXAMPLE III A catalyst comprising approximately 9%,of

titanomolybdic acid distended on a synthetic gel type alumina was prepared in the following manner: Approximately 5 parts of freshly prepared titania gel was slurried with 200 parts of water and 14 parts of sodium fluoride and heated to boiling. '70 parts of molybdic acid were added together with 10 parts of sodium fluoride in the presence of 100 parts of water and 100 parts of hydrochloric acid. The reaction solution was extracted with ether to yield the ethercomplex of the titanomolybdic acid. The acid was iso-, lated as a water solution from the other complex and employed to prepare the catalyst in the same manner as shown in Examples I and II above.

It is also possible to prepare catalysts of this type without the necessity of going through the somewhat tedious and expensive acid. purification step. Such preparation is illustrated by the following examples in which only a few of th 1 many possible catalysts are shown.

EXAMPLE IV A catalyst comprising approximately 11.1% by weight of zinc phosphomolybdate distended on a synthetic highly purified alumina gel was prepared as follows: 500 parts of molybdenum trioxide, 140 parts of phosphoric acid, 35 parts of nitric acid and 2,000 parts of water were mixed and heated for approximately one-half hour at C. to yield crude phosphomolybdic acid. After separation of the solution from the unreacted molybdenum trioxide the acid was iso-- lated by ether extraction and to '75 parts of the acid in 450 parts of water 42 parts of zinc nitrate hexahydrate was added to form the zinc phosphomolybdate in acid solution. Approximately 410 parts of the synthetic alumina gel which had been previously calcined for two hours at 600 C., was immersed in the zinc phosphomolybdate.

solution. for a period of 85 minutes. The impregnated alumina was removed from the impregnated solution, dried for 16 hoursat 0.;

were made by a process similar to the above comprising cobalt phosphomolybdate on a synthetic alumina carrier, cobalt phosphotungstate on an alumina carrier and aluminum phosphomolybdate on the same carrier.

A catalyst comprising phosphomolybdic acid on bauxite was prepared by impregnating the bauxite with the reaction products of molybdenum trioxide, phosphoric acid, nitric acid and water extraction of the phosphomolybdic acid from the reaction product. Again it was found that the presence of the excess phosphoric and nitric acid had substantially no effect on the corresponding metallic nitrate to a portion of the above reaction solution containing the phosphomolybdic acid with subsequent impregnation oi bauxite with each of these metal phosphomol'ybdateso'lutions. As previously described if an excess of the metallic nitrate is employed the unreacted phosphate ion will be removed from the solution as an insoluble metal phosphate resulting in a purer heteropoly acid salt solution.

In another method of preparing the catalysts according to my invention simple mechanical mixing of the desired catalytic agent and the carrier may be employed. This procedure may be accomplished by eitherisolating the heteropoly acid or its salt inthedry state and subsequently mixing the dried acid or salt with the desired quantity of alumina, silica, titania, zirconia,

magnesia, zinc oxide, thoria, mixtures of these,

or the l'ike, pil-ling or'otherwise forming the catalyst"par'ticles and calcining at a relatively high temperature such as in the range of about 300 C. to about 800 C. to yield the desired catalyst. Alternatively a calculated amount of a solution of the heteropoly acid or of the salt thereof may be mixed with a carrier so as to result in-a paste substantially free of excess solution which paste may be formed in any desired shape prior to or after drying and activation. This latter method-diners somewhat from the method of impregnation as described above in that there is no excess solution and no question of separation of the carrierfrom the excess catalytic agent.

In yet another method of preparation of these.

catalysts an organic complex of the heteropoly acids may be prepared to effect the purification of the acid or salt and this complex used directly to impregnate, or otherwise combine with, the desired carrier 'W-hereafter the carrier is heated in the presence of air to a temperature sufficiently high to burn off the organic complex forming compound thus leavingithe uncombined heteropoly acid or salt on the carrier. As organic compounds for the formation of these complexes lmay use any nitrogen, sulfur or oxygen containing organic compound which is capable of forming a complex with the heteropoly acids, 'but I have found that the nitrogen or amine type compounds of the structural formula R--NH are superior for this purpose inasmuch as their usage results i-n a more eilicient extraction of the acid or salt from the reaction solution. Thus, in the preparation of :a' catalyst comprising for example, chromotungstic acid, the crude reaction products :containing the chromotungstic acid as well'as contaminating iOl'lS may be extracted with pyridine, whereby the pyridine complex of the acid separates as a solid phase from the reaction products and may be separated therefrom :and employed directly to combine with a carrier selected from the class described above. The catalyst is then subsequently heated to the temperature in the range of approximately 300 C. to about 300 C. for a period-of=time ranging from about one hour to about-six hours to effect the decomposition of the pyridine-chromotungstic acidcomplex and the removal of the organic constituents from :the catalyst by oxidation at'these temperatures.

.In a fourth method of preparing a finished catalyst employing catalytic agents of the presentlinvention, I may ."form "an inorganic -decom- Possible salt of the. desired .heteropolyi acid 'asla. means of extracting the acid fromithe reaction solutionand employ a solution of this inorganic salt directly as the impregnating solution or com? bine the solid salt with the carrierandsubse+ quently calcine the impregnated carrier at fi-a' temperature sufficiently highto decompose-the salt and leave the heteropoly acid distended on the carrier.

may. separate the acid from thereaction: prod ucts by addition of ammonium nitrate, chlorideor the like tothereaction solution to form am:

monium'phosphomolybdate salt which is then removed as an insoluble precipitate from the solution, dissolved in acidand the resultant sol-u tionemployed directly to impregnate the desired carrier. Alternatively the ammonium phosphomolybdate may be mixed with a-carrier in dry form and the mixture pilled or otherwise formed and heat treated to decompose the ammonium salt to the heteropoly acid. Such usage of the inorganic salts of the heteropoly acidispa rtic ularly desirable in the formation of ammonium the impregnation of the carrier up decomposi tion of the ammonium salt upon heat treating at a temperature in the range of 300 C. to SOO C. may result'in the formation of the correspond: ing heteropolyaoid salt of such contaminating metal ions as sodium, calcium, magnesium, or the" like. As pointedout-a'bove the formation or such a salt with these contaminating ions has the ef fect of minimizing their deleterious effect on the destructability of the carrier. Possibly the great} est benefit from this method of preparation is the formation of a cheap pilled catalyst. Although I have described numerous-methods of preparing the catalyst according to the 'pres entinventionI do not wish to be limited thereby inasmuch as the invention is directed primarily to the newand improved catalyst and secondarily to preparation methods and therefore other methods of preparation which may-occur-to' those skilled in the art should not be construed as falling outside the. principles of the present invention.

The carriers to be employed in the preparation of these catalysts will of necessity vary with the particular catalyst to be prepared. In most preparation procedures these carrier materials are pretreated in some manner such as by cal cination at elevated temperatures; acid treatment, or the like to improve their characteristics in thefinal catalyst with relation to suchfactors as surface area, :degree of purity and the'like'.

It is within the scope of the present invention to employ any desiredmethod of pretreating the selected carrier, .but best results appear to beobtained when :the carrier is at some time prior to the completion or the catalyst calcined at Ia tem perature in the range of about 300 C. to about 800 C. and preferably in the range about-500 C to about'TOO" C. The stage at which this ca lcmationgis "most effective is dependent uponthe method of catalyst preparation employed. It

Thus in my method of preparinga phosphomolybdic acid containing catalyst I A substitution may occur within the the catalytic agent is to be distended on the carrier by means of impregnation from a solution containing the catalytic agent, it is desirable to calcine the carrier at a temperature in the above range prior to the impregnation, but on the other hand, if the catalyst is to be prepared by mixing the catalytic agent with the carrier, the latter being either dry or in gelatinous form the calcination is most effective after the mixture has been made. Although such calcination represent the preferred procedure in making these catalysts, other methods may be employed which may always yield effective catalysts containing the components as disclosed herein. Similarly there are many ways of treating a catalyst prior to usage to increase its activity, heat stability, mechanical strength or the like all of which may be employed within the scope of the present invention. Thus the'catalysts as disclosed may be in powder form, granules, pills or any desired shape. The forming of the catalyst may be accomplished prior to or subsequent to the combination of the catalytic agent with the carrier. In general it is preferred, in those cases where the catalytic agent is combined with the carrier by means of impregnation of the carrier from an aqueous or other solution of the catalytic agent, to form the carrier into the desired shape prior to this impregnation. Conversely if the catalytic agent and carrier are to be combined by mechanical mixing it is preferable to form the catalyst after the combinationhas been affected. Also in most cases I have found that best catalytic results are obtained if the combined carrier. and catalytic agent, he, the catalyst is heated to a temperature in the range between. about 300 C. and about 800 C. for a period of from about 1 to about 4 hours. The preferred temperatures for this heat treatment lie between about 400 C. and about 650 C. and the optimum time oftreatmen-t has been found to be about Z'hours. It is to be emphasizedthat these considerations ar not to be construed as establishing limitations of the present inventioninasmuch as any method of treating the catalyst maybe employed dependent upon the choice of the individual uses.

In many catalytic reactions a catalyst is employed which may be said to be comprised substantially completely of the catalytic agent in the absence of any carrier or supporting material. Such usage is illustrated for example in the desulfurizationof sulfur containing hydrocarbons wherein a mixture of the combined oxides of cobalt and molydenum has been employed in the absence of supporting alumina or other carriers. Suchcatalysts may also be prepared and used according to the present invention by calcining theacids-or salts as herein disclosed in the absence of carrier material. I have found. that such: application is more effective with the metal salts of the heteropoly acids than with the acids themselves and particularly those. metal salts in which the salt forming metal ion is selected from the class of elements comprising alumina, zirconia, titania, magnesia, cobalt oxide, thoria, or the like are the most satisfactory. Thus such catalysts as cobalt phosphomolybdate, "cobalt phosphovanadate, cobalt silicontungstate, and the like are effective desulfurizationcatalysts while siichcatalysts s s-aluminum boromolybdate, aluminum phosphomolybdate; titanium phospho- Inplybdate ferric; silicomolybdate, and the like are fi ct ye hydr form nsca s; e c; L

The foregoing description illustrates the type of catalysts and methods of preparing these catalysts which I may employ to catalyze high temperature hydrocarbon conversion "processes such as the hydrogen exchange processes including dehydrogenation, desulfurization, hydrogenation, hydroforming, aromatization, and'the like, molecular reforming processes such as cracking, alkylation, desulfurization, condensation, and the like, addition processes such as nitration, chlorination, bromonation, hydration, and the like, and isomerization processes, which conversion processes are generally carried out at temperatures in the range of about 50 F. and to about 1500 F. and at pressures in the range of about --14 pounds persquare inch to as high as 1,000 pounds per square inch or higher. For these processes, I may employ catalysts comprising a catalytic agent consisting of the heteropoly acid or a salt of the heteropoly acid which catalytic agent may or may not be distended on a suitable carrier. The preferred catalysts according to the present invention comprise the heteropoly acids or the salts of the heteropoly acids, and preferably those acids or salts containing phosphorus as the central ion, as the catalytic agents distended on alumina of either natural or synthetic origin.

Thus in the process known as hydrof-orming a selected hydrocarbon feed i subjected to the action of the catalyst at temperatures in the range of about 700 F. to about 1200 F., and preferably in the range of about 850 F. to about 1050 F., and at pressures of about to about 500 pounds per square inch or higher in the presence of a hydrogen'ri-ch recycle gas whereby a substantial portion of the hydrocarbon feed is converted to aromatic hydrocarbons. Also in a hydrocarbon" conversion process known as desulfurization sulfur containing hydrocarbons are passed over the catalyst at temperatures rangin f-romas low as about 500 F. to as high as about 1,000 F. but preferably in the range of about 600 F. to about 900 F. and at pressures in the range of a few atmospheres to about 1,000 pounds per square inch or higher. The desulfurization is more complete if the reaction is carried out in the presence of a hydrogen rich recycle gas.

The dehydrogenation of the normally gaseous.

hydrocarbons as well as the normally liquid hydrocarbons in the presence of catalysts of the present invention may be carried out at temperatures in the range of about 900 F. to about 1500 F. and preferably in the range of about 1,000 F.

r to about 1,200 E. at pressures in the range of ll pounds per square inch to atmospheric or above. In the dehydrogenation of certain hydrocarbons particularly those containing an unsaturated linkage it may be desirable to include in the feed to the reaction an inert diluent such as steam, nitrogen, carbon dioxide or the like, or a gas which may function as a hydrogen acceptor such as a lower molecular weight olefin, diolefin, or the like.

In certain of its aspects the process of arcmatization is analogous to the process of dehydrogenation and hydroforming, and for this reason the preferred catalysts for the aromatization reaction are those in which the catalytic agent comprises a heteropoly acid or a heteropoly acid salt containing both chromium and molybdenum such as for example chromium phosphomolybdate, chromiomolybdic acid, chromium germanemolybdate, chromium arsenomolybdate, and the 1'9? like. In the process of aromati'zation the hydrocarbon feed, normally substantially parafilnic in nature, is passed over. the catalyst at a temperature in therangeof'about. 600 F; to about 1,000 F. and preferably in the. range of about 700 F. to about 900 F. at pressuresin the range of about atmospheric to 100 pounds per square inch or greater. The aromatizationreaction may be carried out either in the presence or absence of a hydrogen rich recycle gas.

l he following examples represent the'uti'lization of only a fewof the catalysts prepared according to the present invention, but areillustrative of the merits of these catalysts.

Two hydroforming' catalysts were prepared using a low iron content bauxite as a carrier upon which was distended in one case 10.0 weight per centof molybdenum trioxide and in the other 8.4 weight per cent of. phosphomolybdic acid. Catalyst No. 1- comprising the molybdenum trioxide distended on bauxite was prepared by in mersing- 250 parts by weight of low iron content bauxite of 820 mesh size in 250 parts of impregnating solution. This impregnating solution was prepared by dissolving 65 parts of ammonium paramolybdate (analyzing 81.8% M003) in parts of 0.9 specific gravity ammonium hydroxn ide. Fifty parts. of water were added to the ammonium hydroxide solution, the resultant solution filtered. and. diluted with water to yield 250 parts or". the impregnating solution. After 15 minutes immersion time. the impregnated bauxite was removed from the solution, dried for 16 hours atapproximately 110. C- and heated for two hours in an atmosphereof air .at 600 C. to convert the adsorbed ammonium m'olybdate to molybdenum. trioxide. The finished catalyst designated as"Catalyst No. 1 analyzed 10.0 weight per cent of M003 on the bauxite carrier. Catalyst No. 2 was prepared by immersing a sample of the same bauxite in an aqueous solution of phosphomolybdic acid as. follows: The phosphomolybdic acid was prepared by heating. a mixture comprising 600. parts by weight of sublimed molybdenum trioxide, 110 parts of orthophosphoric acid, 100 parts of concentrated nitric acid. and 1,000 parts of water to 65-85 C. for three hours accompanied by continual agitation. The supernatant liquid wasv decanted from the unreacted M003, filtered and extracted with ether to yield approximately 110 parts by Weight of the ether complex of the acid. This complex was dissolved in an equal volume of water and the ether was removed by bubbling air through the solution under vacuum. The resulting concentrate was diluted with -water to the ratio of 243 parts of phosphomolybdic acid to 250 parts of water and the catalyst was prepared by immersing 500 parts of 8-20 mesh, low iron bauxite in 555 parts of this solution for 2 hours, drained, dried for 16 hours at 110 C. and heated for two hours to 600 C. The finished catalyst contained 8.4 per cent by weight or phosphornolybdic acid.

Catalysts 1 and 2 were tested for hydroforming activity when fresh and after a heat treatment for six hours at 800 C. by passing a feed comprising a 200 F. to 260 F. boiling range naphtha fraction over each catalyst sample at 950 isothermal block temperature, 100 pounds per square inch gage pressure, at a'liquid hourly space velo'c ity of 1.0 and with 3,000 cubic feet of hydrogen rich recycle gas per barrel of feed. The aromatic synthesis reported'in; Table 1 was taken in each case as a measureof theyhydroforming activity of each catalyst;

Ta'hZeNo. 1

Further the heat stability of Catalyst No; 2 is:

considerably better than that of; Catalyst No. 1, the former losingjapproximately 12% of its freshv activity as. compared to a loss of approximately 43% suffered by the latter; As previously described the improvement of heat. stability is attributed to the use'of the molybdenum in com.- bined form whereby it may beconsidered. to be. less available to acceleratetheloss in activity of the carrier- Yet another. advantage of the, catalysts of the presentinvention is, evidenced by the. data of Table 1, that being the reduction of the. cracking characteristics. of the catalyst. This eifect is apparent by comparisonjof the 68.6% liquid yield from Catalyst No. 1 and'th-e 77.2%

liquid yield from Catalyst No. 2; at substantially the same level of hydrof'orming activity.

EXAMPLE VI- A third hydroforming catalyst comprising silicomolybdic acid distended on low iron content bauxite was prepared, as follows: 300 parts of sodium molybdate was dissolved into 1200 parts of water to which solution wasadol'ed 120 parts of concentrated hydrochloric acid. This solution was vigorously stirred and 30 parts of 10 Baum sodium silicate dissolved in 300 parts of water was slowly added. Subsequent; to this addition 360 parts, of concentrated hydrochloric acid was added to the mixture. The resultant solution was extracted with ether to give the ether acid complex. 'The ether'complexcontaining sodium ion as an impurity was washed twice with a solution of 3 to 1 dilution-of concentrated nitric acid; An equal volume of waterwas added to the purified extract and the ether removed by bubbling air through the mixture under vacuum. A catalyst was prepared by immersing 500 parts of the 8 to 20 mesh low iron bauxite employed in the preparationof Catalysts 1 and 2' in a solution comprising267 parts of a silicomolybdic acidwater concentrate diluted to 5515 parts with water. After an immersiontime or 2. /2 hours the. impregnated bauxite was. drained: and dried for 16 hours at C;.'a'nd subsequently heattreated for two hours at 600- C. "The resultant catalyst designated Catalyst No. 3 comprisedapproximately 8% by weight of. silicomolybdic acid distended on the 8130-20 mesh bauxite. This catalyst was tested for hydroiorming activity according to the procedure outlined in Example V when fresh and after asix hour heattreatment at 800 C. The results of these activatio'nftests are given in Table 2 in which the activity. data for Catalyst No. 1 is repeated for purposes of comparison.

Table No. 2

Catalyst No. 1 Catalyst No. 3

M003, Wt. percent 10.0 10.0 1 8. 0 1 8.0 Heat Treatment Temp, "C Fresh 800 Fresh 800 Test Data:

Product Yield, vol. percent 68.6 83. 7 68.4 77.2 Product Gravity, A. P. I... 42. 0 50. 3 41. 6 44. 6 Synthetic Aromatics, Vol.

percent 34. 3 19. 6 35.1 34. 2

1 Present as silicomolybdic acid.

It is seen from these data that the combination of the molybdenum with the silica in the form of silicomolybdic acid greatly improves the heat stability of the catalyst as evidenced by a loss of activity of the silicomolybdic acid catalyst of some 2% and of the molbydenum trioxide catalyst of 43%. Further, by comparison of the data for Catalyst No. 3 and the data for Catalyst No. 2 the latter containing phosphomolybdic acid, it is apparent from the yield values and product gravities that the presence of the silica induces a destruction of the feed greater than that of the phosphorus containing heteropoly molybdic acid. However, this destruction due to the presence of silica is not substantially different from that occurring when employing molybdenum trioxide as the catalytic agent as evidenced by the gravities and the yields shown for the fresh catalyst No. 1.

EXAMPLE VII Another effective hydroforming catalyst utilizes the aluminum salt of the phosphomolybdic acid as the catalytic agent. To prepare such a catalyst 32 parts of aluminum nitrate was dissolved in a solution of 224 parts of phosphomolybdic acid concentrate diluted to a total of 555 parts with water. 555 parts of the same 8 to 20 mesh low iron bauxite was immersed in this solution for 110 minutes subsequently drained, dried for 16 hours at approximately 100 C. and heat treated for two hours at 600 C. This catalyst was tested for hydroforming activity as in the above example yielding a synthesis of aromatics of approximately 34% when fresh and approximately 33.1% after heat treatment at 800 C. for six hours. It was found that the activity and heat stability of this catalyst which comprised approximately 9.0% of aluminum phosphomolybdate distended on the low iron bauxite, is substantially equal to the heat stability and activity of the phosphomolybdic acid and silicomolybdic acid catalysts.

EXAMPLE VIII Two desulfurization catalysts were prepared, one comprising the combined oxides of cobalt and molybdena distended on a gel type alumina, and the other cobalt phosphomolybdate distended on the same aluminum. Catalyst No. 4 comprising the combined oxides of cobalt and molybdena distended on alumina was prepared by impregnation of the alumina carrier with a solution containing salts of cobalt and molybdenum. This impregnation solution was prepared as follows: 173 parts by weight of ammonium paramolybdate containing 82.2% of molybdenum trioxide was dissolved in a solution of 450 parts by weight of .9 specific gravity ammonium hydroxide and 300 parts of water. To this ammonium molybdate in ammoniacal solution was added 150 parts by weight of a 3.43 molar cobalt nitrate solution.

The catalyst was prepared by immersing 300 parts of 8 to 20 mesh synthetic alumina gel, which had been previously heat treated for two hours at 600 C., in 400 parts of the above impregnating solution. After fifteen minutes immersion the impregnated alumina granules were drained, dried for sixteen hours at approximately 110 C. and heat treated for two hours at 600 C. to yield the final catalyst comprising approximately 9.7% of the combined oxides of cobalt and molybdenum and approximately 90.3% by weight of alumina.

Catalyst No. 5 comprising approximately 9% of cobalt phosphomolybdate on the same syn thetic gel type alumina was prepared as follows: 36a parts of a concentrated phosphomolybdic acid solution was mixed with 59 parts of cobalt nitrate hexahydrate and this mixture diluted with water to give a total of 700 parts by weight. 575 parts of the 8 to 20 mesh alumina previously heat treated for two hours at 600 C; was immersed in the solution of cobalt phosphomolybdate for 45 minutes. The impregnated alumina was drained, dried for approximately 16 hours at C. and heat treated for two hours at 600 0.

Each of these catalysts was employed to desulfurize a heavy straight run gas oil with a boiling range of 395 F. to 650 F. and containing 2.28 weight per cent of sulfur determined by the ASTM bomb method. A six hour run was made with a sample of each catalyst as prepared and after an 800 C., six hour heat treatment. The conditions of operation were a liquid hourly space velocity of 2, a pressure of 150 pounds per square inch gage, 750 F. isothermal block temperature and with 3,000 cubic feet of :a hydrogen rich recycle gas per barrel of feed. It is realized that these conditions of operation are not optimum for gas-oil desulfurization inasmuch as an increase in pressure or a reduction in space velocity will affect a greater degree of sulfur removal but were arbitrarily chosen for standard test conditions. The results of these activated tests are tabulated in TableB below:

1 Present as cobalt phosphomolybdate.

EXAMPLE IX 7 Another desulfurization catalyst was prepared in a manner similar to that of Catalyst No. i comprising approximately 7.9% by weight of the combined oxides of cobalt and molybdenum distended on 8 to 20 mesh low iron content bauxite and is designated Catalyst No. 6. Catalyst No. 7 comprising approximately 8% by weight of ferric phosphomolybdate distended on the same bauxits was prepared as follows: 206 parts of phosphomolybdic acid concentrate, 30 parts. of concentrated nitric acid and 61 parts of ferric nitrate (Fe(NOs)3'9Il2C) were dissolved and diluted to 480 parts with water. 500 parts of the 8 to 20 mesh bauxite was immersed in this solution of ferric phosphomolybdate for 80 minutes. The impregnated bauxite was drained, dried for 16 hours at C. and heat treated for two hours at 600 (3. Each of these catalysts was tested for desulfurization activity as in Example VII when fresh and after heat treatment at 800 C. for six Catalyst No. 6 Catalyst No. 7

Catalytic agent, we 7. 9 2 7. 9, 2 S. 2 8.0 Heattreatment C Fresh 5300 Fresh 800 S in product, Weigh 182 2 70 190 203 1 Present as cobalt molybdate. 2 Present as ferric phosphomolybdate.

t is apparent from ExamplesVII and VIII that the catalysts of the present invention in which the cobalt and molybdenum or iron and molybdenum are present on the catalyst in the form of a heteropoly salt yield a catalyst of greater heat stability than when the catalytic agent consists simply of the combined oxides of the metals.

Catalysts oi the above type, comprising iron, cobalt and nickel or other group VIII metal salts of the heteropoly acids, are especially suitable for addition reactions, such as hydration or aminination of olefins to produce alcohols or amines. The latter reactions are generally carried out at temperatures in the lower portion of the above range, for example about 506 to 700 R, at rela-- tively high pressures, such-as about 500 to about 5909 pounds per square inch, in the presence of water or ammonia respectively, in amounts between about 10% and 75% of the gaseous feed mixture. Thus the cobalt phosphomolybdate Catalyst N0. 5 above was used for hydration of propylene at a temperature of 500 F. and a pressure of 509 pounds using 50% water vapor in the feed, to obtain a yield of about isoprop'anol, substantially the equilibrium value. Similarly, at 556 F; and 1600 pounds gage, a steam, 75% ethylene feed was used'to obtain a yield of about 2.5%, also very ear the maximum theoretical value. With Catalyst No. '7, the iron phosphomolybdate on bauxite, results almost as good were obtained. A nickel 'phosphomolybdate on bauxite Was prepared in a manner entirely similar to Catalyst No. 7 using nickel nitrate in place of the ferric nitrate. The resulting catalyst was employed in the preparation oiisopropyl amine from propylene. In this reaction, a temperature oi about 600 F. was employed, a pressure of I about 500 pounds gage, and a gaseous composition containing about equal parts of ammonia and propylene as feed. The conversion to the amine was about 75 of the theoretical. A cobalt silico-molybdate on alumina catalyst was prepared by impregnating the alumina solution containing sodium molybdate and sodium silicate partially acidified with nitric acid and subsequently passed through a commercial ion exchanged resin to convert the sodium ions to hydrogen ions prior to impregnation. Following the impregnation of the above solution, and drying, the impregnated alumina was dipped in a solution of cobalt nitrate to convert the silicomolybdic acid to cobalt silicomolybdate. The resulting catalyst was used in the conversion of the butenes a refinery butane-butene mixture, bypassing a mixture containing about equal parts of ammonia and the refinery butane-butene mixture over the above catalysts at a temperatureof about 500F. and a pressure of about too pounds gage. The product contained a substantial proportion of butyl amines and unconverted butane. Similar good-results are obtain- 24 able for addition reactions, using the other group VIII metal salts of the heteropoly acids.

It is to be understood that these examples are not intended tolimit my invention inasmuch as other catalysts have been prepared and used in these and other hydrocarbon conversion processes and the present invention includes the usage and preparation of catalysts comprising a heteropoly acid or a heteropoly acid salt either distended on a suitable carrier or in itself for catalysts for the hydrocarbon conversion process.

This application is a continuation-in-part of my copending application SerialNo. 619,693, filed October 1, 1945 now U. S. Patent 2,547,330.

Having described and illustrated the principles of my invention and realizing that many mo-tli fications thereof may occur to those skilledin the art without'departing from the spirit and scope of the invention, I claim:

1. A catalyst consisting essentially of a major proportion of a carrier of the group consisting of the inorganic metal oxides and hydroxides and impregnatedthereon a minor proportion between about 3% and about 20% of a nickel salt of a heteropoly acid.

2. Acatalyst consisting essentially of a major proportion of a carrierselected from the class of compounds consisting of "the inorganic metal oxides and hydroxides and impregnated thereon a minor proportion between about 3% and about 20% of a compound selected from the class or" the zinc, iron, cobalt and nickel metal salts of the heteropoly acids.

3. A catalyst according to claim 2 in which the heteropoly acid contains molybdenum.

4. A catalyst according to claim 2 in which the compound present'in minor proportion is a metal salt of a heteropoly acid in which the central atom is phosphorus.

-5. A catalystconsisting essentially of a major proportion of a carrier selected from the class of compounds consisting of the inorganic metal oxides and hydroxides and impregnated thereon minor proportion between about 3% and about 20%01 a cobalt salt of a heteropoly acid.

6. A catalyst'consisting essentially of a major proportion'of a carrier selected from the class of compounds consisting of the inorganic metal oxides and-hydroxides and im regnated thereon a minor proportion between about 3% and about 20% of a zinc salt of a heteropoly acid.

7.1% catalystconsisting essentially of a major proportion of alumina and impregnated'thereon a minorproporvion between about 3% and about 20% of a nickel salt of phosphomolybdic acid.

'8. A catalyst consisting essentially oi'a major proportion of alumina and impregnated there on a minor proportion between about 3% about 20% of cobalt phosphornolybdate.

9. A catalyst consisting essentially of a major proportion of alumina and impregnated thereon a minor proportion between about 3% and about 20% of cobalt silicomolybdate.

1i). A method of preparing a catalyst comprising'a metal salt of phosphomolybdic acid distended on alumina which comprises commingling sublimed molybdenum trioxide, phosphoric acid, nitric acid and water, heating the resultant mixture'to' a temperature in the range of about 60 C.,to' about C. for a period of about 1 hour to about 5 hours to form phosphomolybdic acid therein, adding thereto a suiiicient amount of a water-soluble salt of the desired metal to form the desired phosphomolybdic acid salt, immersing said alumina carrier inthe resultant solution 25 whereupon a portion of the phosphomolybdic acid salt in said solution is adsorbed by said alumina carrier, drying said impregnated alumina carrier at a temperature of about 100 C. and heat treating said carrier at a temperature in the range of about 400 C. to about 800 C.

11. In a method of preparing a material selected from the group consisting of silicomolybdic acid, silicotungstic acid, phosphomolybdic acid, and phosphotungstic acid, and metal salts of said acids, wherein said metal salts are formed by adding to an aqeous solution of said acids a water-soluble salt of the desired metal, the improvement which comprises forming said aqueous solution of said acids by dissolving one soluble salt selected from the group consisting of the soluble metal molybdates and tungstates with a second soluble salt selected from the group consisting of the soluble metal silicates and phosphates, and treating the resultant solution with a solid ion exchanger to convert the cation to hydrogen ion.

12. A catalyst according to claim 2 in which the carrier consists essentially of alumina.

13. A catalyst according to claim 12 in which the heteropoly acid is a molybdenum-containing heteropoly acid.

14. A catalystaccording to claim 13 in which the heteropoly acid is a phosphomolybdic acid.

15. A catalyst according to claim 14 in which the compound is a zinc salt of phosphomolybdic 16. A catalyst consisting essentially of a major proportion of a carrier of the group consisting of the inorganic metal oxides and hydroxides, and impregnated thereon a minor proportion between about 3% and about 20% of an iron salt of a molybdenum-containing heteropoly acid.

RAYMOND N.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS OTHER REFERENCES Kingman et al.: Nature, March 28, 1936 pg. 529.

Claims (1)

1. A CATALYST CONSISTING ESSENTIALLY OF A MAJOR PROPORTION OF A CARRIER OF THE GROUP CONSISTING OF THE INORGANIC METAL OXIDES AND HYDROXIDES AND IMPREGNATED THEREON A MINOR PROPORTION BETWEEN ABOUT 3% AND ABOUT 20% OF A NICKEL SALT OF A HETEROPOLY ACID.